# Compression Only & Surface Spring Validation file

**URL:** <https://prepomax.discourse.group/t/compression-only-surface-spring-validation-file/1275>\
**Category:** General Questions\
**Created:** [November 21, 2023, 10:44pm UTC](https://prepomax.discourse.group/t/compression-only-surface-spring-validation-file/1275 "2023-11-21T22:44:40Z")\
**Posts on this page:** 4\
**Page:** 2

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**Author:** ![FEAnalyst](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/feanalyst/32/688_2.png) [@FEAnalyst](https://prepomax.discourse.group/u/FEAnalyst)\
**Post date:** [November 28, 2023, 7:20pm UTC](https://prepomax.discourse.group/t/compression-only-surface-spring-validation-file/1275/21 "2023-11-28T19:20:03Z")

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> [@synt](#):
>
> hopefully, the solver code of CalculiX made changes to do improvement in the future.

Perhaps it’s worth reporting in the issues section of the CalculiX GitHub repository: [GitHub - Dhondtguido/CalculiX: This repository contains the source files of CalculiX, a three-dimensional Finite Element Program (www.calculix.de).](https://github.com/Dhondtguido/CalculiX)

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**Author:** ![synt](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/synt/32/4658_2.png) [@synt](https://prepomax.discourse.group/u/synt)\
**Post date:** [November 29, 2023, 8:13am UTC](https://prepomax.discourse.group/t/compression-only-surface-spring-validation-file/1275/22 "2023-11-29T08:13:43Z")

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i have been posted this issue in CalculiX forum, another FE solver also treats gap (compression-only) and link (tension-only) element as nonlinear and iteration is required. However, large deformation is not mandatory to be included in analysis.

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**Author:** ![Matej](https://avatars.discourse-cdn.com/v4/letter/m/a698b9/32.png) [@Matej](https://prepomax.discourse.group/u/Matej)\
**Post date:** [November 29, 2023, 12:05pm UTC](https://prepomax.discourse.group/t/compression-only-surface-spring-validation-file/1275/23 "2023-11-29T12:05:25Z")

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I could change how PrePoMax works. I could multiply the stiffness by 2 if no items that require the nonlinearity are present in the model, but this could be tricky. A user might use the \*import keyword and import some contacts into an otherwise linear analysis.

So a better option would be that CalculiX fixes this behaviour.

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<div class="post-metadata">

**Author:** ![synt](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/synt/32/4658_2.png) [@synt](https://prepomax.discourse.group/u/synt)\
**Post date:** [November 29, 2023, 1:14pm UTC](https://prepomax.discourse.group/t/compression-only-surface-spring-validation-file/1275/24 "2023-11-29T13:14:58Z")

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indeed, it should be in the solver when an improvement is possible.

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